A tennis ball is thrown straight up with an initial speed of 20.5 m/s. It is caught at the same distance about ground as it is thrown.

Answer: 21.4 m

Time in air = 2 x 2.09 = 4.18 s

Explanation:

v (f) ² = v (i) ² + 2as

Take up as positive direction

0 = 20.5² - 2 * 9.8s

s = 21.4 m

So the ball rises to 21.4 m

(b) v (f) = v (i) + at

0 = 20.5 - 9.8t

t = 2.09 s [this is the time to max height]

Because the ball returns to exactly the same height from which it was thrown, time up = time down

So time in the air = 2 x 2.09 = 4.18 s